The present invention relates to a power shutoff device, particularly, to a connector-type power shutoff device which is installed between a power source and a load.
Generally, if a power source circuit which supplies power to a load includes a connector, by separating the connector, the load may be separated from the power source so that the load may be checked or maintained safely. However, when the power is cut off by detaching the connector, due to the load, an arc is produced between connector terminals of a plug connector and a receiving connector which are separated, thereby damaging the connector terminals or the like. Thus, in the operation of separating the fitted connector, two steps are performed in which a time lag is included. That is, a power shutoff device is proposed for which an action to make the connector shifted from a fitted state to a detached state is detected, a relay contact which is installed in the power source circuit is opened by the detection signal to cut off the power, and then the connector becomes detachable (for example, a patent document 1).
In the power shutoff device disclosed in the above patent document, an operation lever is rotatably and pivotally supported by the plug connector of the connector which is installed in the power source circuit, the operation lever is connected to the receiving connector, and the operation lever is rotated between a first position where the receiving connector and the plug connector are separated and a second position where the receiving connector and the plug connector are fitted. To detect the operation of separating the connector, the operation lever is formed to be slidable at the second position of the operation lever where the connector is fitted in a direction which is different from the direction that the operation lever is fitted, and a fitting detecting connector, which is formed of a fitting detecting plug connector and a fitting detecting receiving connector which are fitted to each other at a third position to which the operation lever slides, is provided on the operation lever and the receiving connector.
Therefore, when the fitting detecting connector is fitted, a fitting detecting signal becomes ON, a relay of a control circuit of the power source circuit is ON, and power is supplied to the load through the connector of the power source circuit. On the contrary, because when the operation lever slides from the third position to the second position to shift to the operation of separating the connector, the fitting detecting connector which was fitted is separated, the fitting detecting signal of the fitting detecting connector becomes OFF, the relay of the control circuit of the power source circuit is OFF, and the power supply to the load is cut off even if the connector of the power source circuit is fitted. Thereby, the arc which is produced when the connector of the power source circuit is separated can be surely prevented even if the connector is separated when the operation lever is rotated from the second position to the first position.
On the other hand, when the connector of the power source circuit is engaged, there is no problem like that the arc is produced when the connector is separated, but connector terminals of the power source circuit may be damaged because a rush current flows due to the load when the connecting terminals are connected. For this point, according to the power shutoff device of the above document 1, because the connector of the power source circuit is fitted without voltage at the second position of the operation lever where the fitting detecting connector is not fitted, that is, at a position where a relay contact of the power source circuit is opened, the connector terminals can be prevented from being damaged by the rush current of the load.
[Patent document 1] Japan Patent Publication No. 2003-100383